Vent condenser for a feedwater heater

ABSTRACT

A vertically disposed feedwater heater has the upper portion thereof sealed by a water seal to form a vent condenser. The water seal comprises a plurality of telescoping skirts and a collar which cooperate to form the seal and allow the shell to be easily removed from the tube bundle.

United States Patent 1 1 1111 3,885,621

Slebodnick May 27, 1975 [54] VENT CONDENSER FOR A FEEDWATER 2,661,190 12/1953 Kirkpatrick 165 1 11 x HEATER 3,722,479 3/1973 Michel l22/49l X Inventor: Robert G. Slebodnick, Collingdale,

Assignee: Westinghouse Electric Corp.,

Pittsburgh, Pa.

Filed: Mar. 29, 1974 Appl. No.: 456,423

US. Cl 165/110; 165/161 1m. 01. F28g 1/00 Field ofSearch.... 165/105, 110, 111,158-161,

References Cited UNITED STATES PATENTS 6/1934 Ehrhart 165/112 X Primary ExaminerCharles J. Myhre Assistant ExaminerTheophil W. Streule, Jr. Attorney, Agent, or Firm-F. J. Baehr, Jr.

[57] ABSTRACT A vertically disposed feedwater heater has the upper portion thereof sealed by a water seal to form a vent condenser. The water seal comprises a plurality of telescoping skirts and a collar which cooperate to form the seal and allow the shell to be easily removed from the tube bundle.

9 Claims, 1 Drawing Figure V O l -.-I I

P/ nErnEm-mmms 3; 885.621

lilllllll FIG. I.

VENT CONDENSER FOR A FEEDWATER HEATER BACKGROUND or THE INVENTION 3 1. Field of the Invention This invention relates to feedwater heaters and more particularly to feedwater heaters having a vent condensing portion disposed therein.

2. Description of the Prior Art Vertically disposed U-tube feedwater heaters having a channel head disposed at the lower end advantageously provides ample room in the upper end closure for a large vent opening and venting from the upper portion of the heater to preclude the possibility of a water leg in the vent piping, which could obstruct the vent and cause faulty operation of the heater. Such feedwater heaters eliminate internal vent piping, providing greater freedom in the establishment of high water and trip levels and allow efficient utilization of the U-bend portions of the tube bundles for the condensing zone. Such heaters herebefore made utilized a seal-off baffle having a minimal clearance adjacent the shell to form the vent condenser chamber, however, minimizing leakage presented a problem because, it requires very close manufacturing tolerances with respect to the shell diameter and that out of roundness of the shell be held within close tolerances increasing the manufacturing cost of the heater.

SUMMARY OF THE INVENTION Among the several objects of this invention is the provision of a water seal, which effectively separates the vent condenser from the remainder of the heater and provides zero leakage therebetween; the provision of a seal, which is self-priming and self-draining; and the provision of a seal, in which close manufacturing tolerances are not required. In general a feedwater heater, when made in accordance with this invention, comprises a vertically disposed shell portion, a plurality of U-shaped tubes forming a tube bundle disposed in the shell, a tube sheet having a plurality of holesfor receiving the ends of the tubes, a tube support sheet disposed transverse to said tubes adjacent the bent portion thereof. The tube support plate having a plurality of holes through which the tubes pass in a tightly embracing relationship and a sleeve portion disposed adjacent the outer periphery of the tube support plate. The sleeve is disposed to extend downwardly from the plate and a collar extends upwardly from the lower end of the sleeve. A seal ring is disposed between the collar and the sleeve and a skirt is disposed between the sleeve and the collar, the skirt is'fixed relative to the shell and the upper end of the skirt is sealed to the shell and fixed thereto by a ring. The sleeve, collar and skirt are cooperatively associated to form a water seal when the heater is operating. The water seal cooperates with the support plate to form a chamber in the upper portion of the shell and a vent nozzle is disposed in the upper portion of the shell to remove non-condensible gases from the vent chamber.

BRIEF DESCRIPTION OF THE DRAWINGS The objects and advantages of this invention will become more apparent from reading the following detail description in connection with the accompanying drawing in which:

The sole FIGURE is a partial sectional view of a feedwater heater incorporating a vent condenser made in accordance with this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail, there is shown a feedwater heater 1, which comprises a vertically disposed cylindrical shell portion 3, the upper end of which is closed by a flanged and dished head portion 5 which has a vent nozzle or opening 7 centrally disposed therein. The lower end of the shell 3 is closed by a channel head 9, which is cooperatively associated with a tube sheet 11. Extending upwardly from the tube sheet 11 area plurality of U-shaped tubes 13, which form a tube bundle. Bends 15 in the U-shaped tubes forming the free end of the tube bundle are disposed adjacent the upper head 5. A feedwater inlet and a feedwater outlet nozzle 17 and 19, respectively, are disposed in the channel head 9 in such a manner as to cause the feedwater to flow through the tubes 13.

A tube support plate 21 is disposed transverse to said tubes 13 adjacent the bent portion 15 thereof. The support plate 21 has a plurality of holes 23through which the tubes pass in a tightly embracing relationship. The I diameter of the support plate 21 is substantially smaller than the inside diameter of the shell 3 providing a large annular space therebetween.

A cylindrical sleeve 25 is disposed adjacent the outer periphery of the support plate 21 and is seal welded thereto. The sleeve 25 extends above and below the support plate 21, the lower extension being considerably greater than the upper extension.

A cylindrical collar 27 extends upwardly from the lower end of the sleeve 25 and is fastened thereto by an annular ring 29, which is disposed between the sleeve 25 and the collar 27 and is seal welded to each, providing the means for uniting the collar 27 and the sleeve 25 in a sealing relationship.

A cylindrical skirt 31 is disposed generally midway between the sleeve 25 and the collar 27. An annular ring 33 is disposed adjacent the upper end of the skirt 31 and above the upper end of the collar 25. The ring 33 is fastened to the shell 3 and skirt 31 by seal welds, which provide the means for uniting the upper end of the skirt 31, the ring 33 and the shell 3 in a sealing relationship.

The sleeve 25, collar 27, skirt 31 and rings 29 and 33 are cooperatively associated to form a water seal, which primes itself when the heater is operating.

The water seal cooperates with the tube support plate 21 to form a vent condenser chamber 35 disposed in the upper portion of the shell 3. The sleeve 25 extends upwardly above the support plate 21 forming a dam around the periphery thereof and when the heater is operating condensate floods the support plate 21, flows over the dam and cascades downwardly filling the space between the lower end of the sleeve 25 and the collar 27 to insure the integrity of the vent condenser chamber 35. The water held within the dam covers the support plate 21 preventing leakage between the tubes 13 and the holes 23 through which they pass.

A vent channel or duct 37 is centrally disposed in the tube bundle and extends through the support plate 21. The upper end of the vent channel 37 is disposed above the upper end of the sleeve 25 to prevent condensate from flowing over the upper edge of the channel 37.

The vent channel 37 has a plurality of orifices or openings 39 spaced lengthwise along one or more sides thereof to form a passageway, which collects noncondensible gases from all portions of the tube bundle and channels them to the vent condenser chamber 35.

As the steam flows on the outside of the tubes it condenses and the non-condensible gases and some steam flows to the inner portion of the tube bundle and through the orifices 39 into the vent channel 37 wherein it flows upwardly into the vent condenser 35 and passes through the bent portion of the tubes 13, wherein the majority of the steam is condensed and the non-condensibles flowing from the bends 15 of the tubes 13 are vented through the vent nozzle 7.

A syphon tube 41 is connected to the ring 29 and is in fluid communication with the annular space between the sleeve and the collar 27. The syphon tube 41 has a tubular portion 43 which extends downwardly from the ring 29, a lower U-bend tubular portion 45, an upwardly extending tubular portion 47, an upper U-bend tubular portion 49 and a downwardly extending tubular portion 51 which extends downwardly below the bottom of the lower U-bend portion. The upper U-bend portion 49 is disposed below the upper end of the collar 27. The diameter of the tube forming the syphon 41 is small compared to the condensate produced in the vent condenser during normal operation of the heater 1 and there is a pressure differential between the vent condenser chamber 35 and the remainder of the heater. The distance between the bends 45 and 49 is greater than the height of the collar 27 so that in normal operation the syphon 41 is inactive. However, when the heater 1 is shut down and the pressure in the vent condenser chamber 35 equalizes with that in the remainder of the heater, condensate flows through the syphon 41 draining the seal formed by the cooperation of the sleeve 25, collar 27 and skirt 31.

The feedwater heater 1 and vent condenser 35 hereinbefore described, advantageously combine a selfpriming and self-draining water seal that eliminates the need for close manufacturing tolerances in the shell 3 to produce an effective seal between the vent condenser 35 and the remainder of the vessel and yet allows the tube bundle 13 and shell 3 to be separated without considering the vent condenser 35. This arrangement also allows for adequate expansion of the tubes 13 with respect to the shell 3 to preserve one of the main advantages of utilizing a U-shaped tube, tube bundle.

What is claimed is:

1. A feedwater heater comprising a vertically disposed shell portion, a plurality of U-shaped tubes forming a tube bundle disposed in said shell, a tube sheet having a plurality of holes for receiving the ends of the tubes, a tube support plate disposed transverse to said tubes adjacent the bent portions thereof, said plate having a plurality of holes through which the tubes pass in a tightly embracing relationship, a sleeve portion disposed adjacent the outer periphery of said plate, said sleeve being disposed to extend downwardly from said plate, a collar extending upwardly from the lower end of said sleeve, sealing means disposed between said collar and said sleeve, a skirt disposed between said sleeve and said collar, said skirt being fixed relative to said shell, and the upper end of said skirt being disposed in a sealing relationship with said shell, said sleeve, collar and skirt being cooperatively associated to form a water seal when said heater is operating, said water seal the sleeve extends upwardly above the support plate.

3. A feedwater heater as set forth in claim 1 andfurther comprising a conduit extending through the support plate and disposed generally parallel to the tubes, said conduit having a plurality of apertures disposed lengthwise therein. i

4. A feedwater heater as set forth in claim3, wherein the sleeve extends upwardly above the support plate and the conduit extends upwardly above the upper edge of the sleeve. A

5. A feedwater heater as set forth in claim 1 and further comprising a syphon tube one end of which is in fluid communication with an annular chamber formed between the sleeve and the collar said syphon tube being so arranged to automatically drain said annular Chamber when the heater is shut down.

6. A feedwater heater as set forth in claim 1 and further comprising an annular plate disposed betweenthe upper end of the skirt and the shell.

7. A feedwater heater as set forth in claim 6,.wherein A the annular plate is seal welded to the shell and the upper portion of the skirt.

8. A feedwater heater as set forth in claim 1, wherein collar. 

1. A feedwater heater comprising a vertically disposed shell portion, a plurality of U-shaped tubes forming a tube bundle disposed in said shell, a tube sheet having a plurality of holes for receiving the ends of the tubes, a tube support plate disposed transverse to said tubes adjacent the bent portions thereof, said plate having a plurality of holes through which the tubes pass in a tightly embracing relationship, a sleeve portion disposed adjacent the outer periphery of said plate, said sleeve being disposed to extend downwardly from said plate, a collar extending upwardly from the lower end of said sleeve, sealing means disposed between said collar and said sleeve, a skirt disposed between said sleeve and said collar, said skirt being fixed relative to said shell, and the upper end of said skirt being disposed in a sealing relationship with said shell, said sleeve, collar and skirt being cooperatively associated to form a water seal when said heater is operating, said water seal cooperating with said plate to form a chamber in the upper portion of the shell and a vent nozzle disposed in the upper portion of said shell, whereby said chamber forms a vent condenser incorporating the bent portion of the U-shaped tubes.
 2. A feedwater heater as set forth in claim 1, wherein the sleeve extends upwardly above the support plate.
 3. A feedwater heater as set forth in claim 1 and further comprising a conduit extending through the support plate and disposed generally parallel to the tubes, said conduit having a plurality of apertures disposed lengthwise therein.
 4. A feedwater heater as set forth in claim 3, wherein the sleeve extends upwardly above the support plate and the conduit extends upwardly above the upper edge of the sleeve.
 5. A feedwater heater as set forth in claim 1 and further comprising a syphon tube one end of which is in fluid communication with an annular chamber formed between the sleeve and the collar said syphon tube being so arranged to automatically drain said annular chamber when the heater is shut down.
 6. A feedwater heater as set forth in claim 1 and further comprising an annular plate disposed Between the upper end of the skirt and the shell.
 7. A feedwater heater as set forth in claim 6, wherein the annular plate is seal welded to the shell and the upper portion of the skirt.
 8. A feedwater heater as set forth in claim 1, wherein the sealing means is an annular plate disposed between the sleeve and the collar.
 9. A feedwater heater as set forth in claim 8, wherein the annular plate is seal welded to the sleeve and to the collar. 